— 93 — 



fermented leaves. The following table, showing the yield obtained by 

 de Jong from Java leaves, is of interest: 





Quantities worked, 









Condition of 



calculated for green 









the leaves 



material 



I st distillate 



2 nd distillate 



Total distillate 



Fresh 



70 kg. 



38 cc. 



114 CC. 



1 5 2 CC. 



Fei mented 



70 „ 



375 » 



30 » 



405 » 



Dried 



70 „ 



360 „ 



49 »» 



4°9 » 



Dried 



70 „ 



3i5 ,» 



69 » 



384 ,t 



Fermented 



70 „ 



35o » 



28 „ 



378 „ 



Fermented 



70 „ 



359 » 



28 „ 



387 ,. 



From the above it is clear that it is quite useless to work up 

 green leaves, because they only yield very little oil, and even in this 

 case the principal quantity was obtained from the second distillation, 

 that is to say, after the leaves had been dried. Much more consid- 

 erable outputs, on the other hand, are obtained from dried and 

 fermented leaves, almost the total oil contained in them being yielded 

 by the first distillation, the second producing comparatively little oil. 

 The total quantity of oil in dried and fermented leaves is about 

 the • same. 



As regards Singapore leaves, similar conditions prevail. In 

 the case of a single distillation, 24 kilos of the leaves in a green 

 state produced 20 cc. oil, but after drying they yielded 77 cc, and 

 after fermentation 86 cc. The small yield of Singapore as compared 

 with Java leaves is due to the fact that in the former case the dis- 

 tillation took place at atmospheric pressure only. 



The great differences in the oil-yield between green leaves on the 

 one hand and dried or fermented leaves on the other, may be traced 

 to the circumstance that the oil cells are placed partly on the sur- 

 face and partly inside the leaf, and that when fresh leaves are dis- 

 tilled almost the only cells from which the oil is liberated are those 

 on the surface. The fading of the leaves which occurs during the 

 drying or fermentation process, renders the cell - membranes more 

 porous, so that the oil contained inside the leaf also can be separated 

 out by distillation. No oil is formed during the drying or fer- 

 mentation, and the proof of this — so far as fermentation is con- 

 cerned — is that the dried leaf yields the same quantity of oil as 

 the fermented leaf. 



The fact that when green material is used the oil-yield is increased 

 in proportion to the steam - pressure and becomes very considerably 

 greater when superheated steam is used, is in conformity with these 

 views. De Jong's explanation of this is that the rise in temperature 

 brought about by the increase of the steam-pressure causes destruction 

 of further cells, resulting in the liberation of more oil. He also proved 

 by experiments that the yield of oil may be greatly increased by 



